Over the past several years the utilization of depth finders in locating schools of fish and bottom structure has become an increasingly popular adjunct to sport fishing. The early depth finders were based on the World War II era sonar which allowed an acoustic signal to be generated and transmitted through the water, reflected by the bottom and returned to a sensing device which, in combination with electronic circuitry, was able to time the transit of the wave through the water and judge the distance of the bottom from the boat. Oftentimes these devices merely presented an indication on a circular scale that stated that the bottom was at thus and such depth and therefore it was necessary to pay close attention to the scale to determine contour of the bottom of the body of water. As these devices have progressed over the years, the state of the art has developed to the point that it is common to employ a recorded graph which automatically traces a pictorial representation of the bottom of the body of water on a strip of paper using pins or other imaging techniques with the strip of paper being retained by the operator. In these instances, of course, a permanent record of the bottom contour along a particular transit line across the water may be recorded and preserved. It will be appreciated that most fishermen do not have a need to record each transit of the body of water but rather are more particularly concerned with the submerged features of the body of water as they are moving over the body of water. This is particularly true in as much as the sensitivity of depth finders has been increased to the point where suspended objects such as fish or schools of fish may be detected by the depth finders and represented on a display screen. Therefore it is now popular to provide depth finders which have display screens such as liquid crystal displays which can give a pictorial representation of not only the bottom of the body of water but also of fish suspended above the bottom of the body of water.
The evolution of the technology has seen a corresponding evolution of the complexity of the data and information required by the fishermen. As the technology has grown, the fishermen has been required to become increasingly adept at operating the depth finder. For example, the depth finder may have a plurality of ranges over which the depth of the body of water may be ascertained. The depth finder may also have a variety of sensitivity selections or functions which the operator needs to learn. Many of these functions have been enabled by the utilization of chip technology with small computers which are actually employed in the circuitry of the depth finders. Therefore, it is not uncommon for the fisherman to be overmatched when dealing with his particular depth finder, that is to say, the fisherman may have more equipment than he is able to handle while maintaining an interest in catching a fish. To this end, it has become apparent that the technical aspects of using a depth finder with its various sensitivity and automation features has reached the level where a need exists for a simplified depth finder which can perform all of the functions that a fisherman wishes to have performed.